Article having multifunctional conductive wire

ABSTRACT

Articles and devices comprising a multifunctional conductive wire having a first electrode including a first carbon nanotube composite yarn containing carbon nanotubes and secondary particles; a second electrode including a second carbon nanotube composite yarn containing carbon nanotubes and secondary particles; a first separator membrane surrounding the first electrode; a second separator membrane surrounding the second electrode; an electrolyte surrounding the first and second electrodes; a flexible insulator layer surrounding the electrolyte; and a flexible conducting layer at least partially surrounding the flexible insulator layer. Also provided are method of making and using the articles, devices, and multifunctional conductive wires herein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/813,516, filed Mar. 4, 2019, and entitled “Composite Yarn and Method of Making a Carbon Nanotube Composite Yarn.” This application claims priority to U.S. patent application Ser. No. 16/446,389, filed Jun. 19, 2019, and entitled “Composite Yarn and Method of Making a Carbon Nanotube Composite Yarn.” This application claims priority to U.S. patent application Ser. No. 16/805,565, filed Feb. 28, 2020, and entitled “Multifunctional Conductive Wire and Method of Making.” The disclosures of the preceding applications are hereby incorporated in their entirety by reference.

BACKGROUND

Devices comprising metal conductive wires, particularly solid or stranded copper wires, have been produced and utilized in many industrial sectors for many decades. However, recent demands for miniaturization of devices and optimization of energy efficiency place new challenging demands on the high volumetric and high gravimetric features of metal conductive wires, so new devices and articles comprising new types of wires are needed. Finding new methods for synthesis, fabrication, and engineering that will add more functions in conductive wires, instead of solely functioning as current carriers, is of central interest. Legacy solid and stranded copper wires, typically functioning solely as power conductors, can add tons of weight to commercial jets. The limitations of legacy solid and stranded copper wires are particularly critical for vehicle motors, for example, in some electric vehicles the motor can include about 76 kilograms of copper coils. Adding additional weight, the batteries in electric vehicles can weigh hundreds of kilograms. Electric motors, generators, and transformers without legacy, solid, or stranded copper coils could have less weight and be more efficient. Thus, new articles and devices having advanced multifunctional conductive wire are needed.

SUMMARY

The present disclosure is directed to articles and devices comprising multifunctional conductive wires and methods of making articles and devices comprising multifunctional conductive wires. Articles with reduced weight and improved efficiency, comprising multifunctional conductive wires (MCW) are enabled herein. The MCW disclosed herein can provide electrical power with less length, weight, and space required compared to legacy conductors. Devices comprising MCW that can have built-in battery function, to simultaneously provide or store power while providing current carriers, are disclosed herein. According to some aspects, MCW can replace solid or stranded copper wires in motors, generators, transformers, and electromagnetic devices. According to some aspects, the MCW disclosed herein can have battery function with two or more electrodes and electrolyte, surrounded by an insulator, with a conducting layer external to the insulator, to form a MCW capable of carrying alternating current as efficiently as a solid copper conductor, yet while also providing a built-in battery. These aspects and other aspects of the present disclosure are disclosed in detail herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows an example schematic for preparing a carbon nanotube composite yarn according to aspects of the present disclosure.

FIG. 1B shows a schematic of two example densification steps according to aspects of the present disclosure.

FIG. 2 shows a Scanning Electron Microscope (SEM) image of a pure carbon nanotube mat according to aspects of the present disclosure.

FIG. 3 shows a photograph of a pure carbon nanotube mat according to aspects of the present disclosure.

FIG. 4 shows an SEM of a carbon nanotube composite mat according to aspects of the present disclosure.

FIG. 5A shows an example MCW cable that includes battery electrodes, according to some aspects of the present disclosure.

FIG. 5B shows an example cross-sectional schematic of an MCW according to some aspects of the present disclosure.

FIG. 5C shows an example cross-sectional schematic of an MCW according to some aspects of the present disclosure.

FIG. 5D shows an example cross-sectional schematic of an MCW according to some aspects of the present disclosure.

FIG. 5E shows an example cross-sectional schematic of an MCW according to some aspects of the present disclosure.

FIG. 6A shows a conventional electrical motor powered by one or more external batteries.

FIG. 6B shows an electrical motor powered by a multifunctional MCW cable that accommodates a battery in the core, according to some aspects of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is directed to articles and devices comprising multifunctional conductive wire and methods of making articles and devices comprising multifunctional conductive wire (MCW). According to some aspects, the MCW can be a wire comprising a core cylinder that is sealed by an insulator layer, which is covered by an outer copper, or any other conductive metal, layer. The core cylinder can be a cylindrical flexible battery that comprises two or more self-standing electrodes (e.g., carbon nanotube yarns with battery active materials) isolated by separator(s) and/or an electrolyte. According to some aspects, the cylindrical flexible battery in the core of the MCW can supply or store power for an electrical device. Depending on the application, one or more outer insulator layers can be applied to the outer conductive layer. Optionally, further layers of conductive material can be applied and further layers of insulating material.

According to some aspects of the MCW, the thickness of an outer conductive metal layer can be varied depending on the intended frequency of an alternating current (AC) to be carried by an outer conductive layer. The thickness can be varied such that conduction of alternating current is optimized, yet without the need for a heavy, central core metal (or copper) material that carries little alternating current. The skin effect is a tendency of an alternating current to have a current density largest near the outer surface of a conductor, with current density into a conductor decreasing with greater depths in a conductor, specifically as the frequency of the AC increases. Skin effect is caused by the back electromagnetic field, with an eddy current, produced by the self-induced magnetic flux in a conductor carrying an alternating current. For a direct current (DC), the rate of change of flux is zero, so there is no back electromagnetic field with an eddy current due to changes in magnetic flux. For a direct current, the current is uniformly distributed throughout the cross section of the conductor. For lower frequency AC, the central core of a solid metal wire carries little current; as the frequency of AC increases, the outer skin of a solid metal wire carries the majority of the current. For higher frequency AC, the central core of a solid metal wire carries no current. Thus, when applied to transmission of alternating current, the MCW disclosed herein can at the core provide a core cylinder battery, where alternating current density would be the least in a solid wire conductor. According to some aspects, providing a core cylinder battery at the core provides a MCW with less weight compared to solid metal wires while simultaneously providing a power source/storage battery in the MCW.

The MCW can also carry direct current (DC). Various components, as known in the art, can be included to convert DC, for example, from the core cylinder battery, to AC for current carrying in an outer conductive metal layer. In another example, AC in an outer conductive metal layer can be converted to DC for storage in a core cylinder battery.

The outer shape of the MCW can be any shape. For example, round or cylindrical shape can be utilized for ease of fabrication or to resemble legacy metal wires. Square shape can, for example, be utilized to maximize efficiency when MCW is wound into a coil. In some electric motors, square shape of MCW can be utilized to maximize winding efficiency and minimize airspace between the windings of a coil. The outer shape can optionally be malleable and flexible.

The devices and articles comprising MCW disclosed herein are not limited by the examples provided. The applications of MCW, for example, include power transmission lines over long distances, which can weigh less utilizing MCW and can store or deliver power at designated areas of the MCW. For example, the MCW can contain (either externally or embedded in) processors, transmitters, receivers, Wi-Fi, sensors, solar cells, and electronic components that determine areas or segments of the MCW that store or deliver power. The MCW can contain diodes or arrays to convert AC to DC. The MCW can contain, for example, fiber optics inside or external, other conductors, other fibers, fasteners. According to some aspects, vehicles, motors, machines, devices, and articles are disclosed herein that comprise MCW. As an illustrative example, a commercial jet comprising MCW can weigh less than a commercial jet comprising solid copper wire, silver-plated, or nickel-plated copper wire. An electrical motor can weigh significantly less using MCW, and such an electrical motor can have increased power to weight ratio compared to motors with solid metal wires. An electrical generator, a large generator in a power plant, or an alternator containing MCW, can weigh significantly less than the same using solid copper wire. Transformers, which contain large coils of wire, can weigh less using MCW. Transmitters, antennae, and inductors are other illustrative examples of devices comprising MCW. Storage of power by the MCW within power lines, vehicles, machines, and devices can reduce or eliminate the need for additional current carriers to carry power to an external storage battery or from an external storage battery.

According to some aspects, a device is disclosed herein that comprises one or more coils of MCW, each coil comprising MCW turned in the shape of a coil, spiral, or helix. Each coil can provide electromagnetic induction/generation while simultaneously providing battery and/or storage capabilities. A coil of MCW can provide or store electrical energy and conduct electrical energy.

According to some aspects, the MCW disclosed herein can comprise two or more flexible electrodes, each flexible electrode comprising carbon nanotube composite yarn, the carbon nanotube composite yarn comprising carbon nanotubes and secondary particles, and optionally one or more separator membranes. According to some aspects, the one or more separator membranes may comprise a distinct separator membrane provided between the two or more flexible electrodes. As used herein, the term “distinct separator membrane” refers to a separator membrane as described herein that is not in direct contact with the two or more flexible electrodes. Additionally or alternatively, each flexible electrode can independently comprise an outer layer of separator membrane. In some examples, the outer layer of separator membrane(s) may eliminate the need for additional separator membranes placed between electrodes. The MCW may further comprise an electrolyte positioned between each of the two or more flexible electrodes.

According to some aspects, the two or more flexible electrodes can be wrapped around each other in a twisted configuration. It is known in the art that twisting two wires around each other significantly reduces electromagnetic interference (also called radio-frequency, RF, interference in the RF spectral region) in the wires. According to some aspects, wrapping or twisting the two or more flexible electrodes around each other can reduce or eliminate electromagnetic interference in the two or more flexible electrodes from alternating current (in the outer conductive layer) or from environmental sources. Optionally, the two or more flexible electrodes can be in a parallel or quasi-parallel configuration or not in contact with each other. A flexible insulator layer that surrounds the two or more flexible electrodes, the optional separator membrane(s), and the electrolyte can contain the two or more flexible electrodes and the electrolyte within the MCW, providing a battery within the MCW. A flexible conducting layer, for example, a metal layer, can surround the flexible insulator layer, with the thickness of the flexible conducting layer varied depending on the frequency of an alternating current carried by the flexible conducting layer. The flexible electrodes inside the MCW are self-standing flexible electrodes due to the carbon nanotubes contained therein. As used herein, the term “self-standing electrode” refers to an electrode capable of function without one or more components provided as a structural support. It should be understood that according to some aspects, any carbon nanotube composite yarn as described herein may be a self-standing electrode.

Methods of making the self-standing flexible electrodes are disclosed herein. A carbon nanotube composite yarn may be made by growing floating carbon nanotubes, continuously removing webs of the floating carbon nanotubes to provide a mat of the carbon nanotubes and, in parallel, depositing secondary particles on at least a portion of the mat of carbon nanotubes to provide a carbon nanotube composite mat, and densifying the carbon nanotube composite mat to provide a carbon nanotube composite yarn.

The method may comprise growing floating carbon nanotubes in a reactor. As used herein, the term “nanotube” refers to a tube having at least one dimension on the nanoscale, that is, at least on dimension between about 0.6 and 100 nm. For example, a nanotube may comprise a tube having a diameter on the nanoscale. According to some aspects, the nanotubes according to the present disclosure may be selected from the group consisting of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs), and combinations thereof.

The floating carbon nanotubes may be grown in a reactor, such as a chemical vapor deposition (CVD) reactor. For example, FIG. 1A shows an example reactor 11 that may be used according to aspects of the present disclosure. As shown in FIG. 1A, the reactor 11 may comprise at least a first inlet 12 in fluid communication with a carbon source chamber 13, the carbon source chamber 13 configured to provide a carbon source, such as a carbon source gas.

Examples of carbon sources include, but are not limited to, one or more carbon-containing gases, one or more hydrocarbon solvents, and mixtures thereof. Specific examples include, but are not limited to, gases and/or solvents containing and/or consisting of a hydrocarbon, an alcohol, an ester, a ketone, an aromatic, an aldehyde, and a combination thereof. For example, the carbon source may be selected from xylene, toluene, propane, butane, butene, ethylene, ethanol, carbon monoxide, butadiene, pentane, pentene, methane, ethane, acetylene, carbon dioxide, naphthalene, hexane, cyclohexane, benzene, methanol, propanol, propylene, commercial fuel gases (such as liquefied petroleum gas, natural gas, and the like), and combinations thereof.

The carbon source chamber 13 may also be configured to provide a catalyst and/or a catalyst precursor, such as a catalyst and/or a catalyst precursor vapor. As used herein, the term “catalyst” refers to a component that provokes or speeds up a chemical reaction, for example, the synthesis of nanotubes. Examples of catalysts useful according to the present disclosure include, but are not limited to, transition metals, lanthanide metals, actinide metals, and combinations thereof. For example, the catalyst may comprise a transition metal such as chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), copper (Cu), silver (Ag), gold (Au), cadmium (Cd), scandium (Sc), yttrium (Y), lanthanum (La), platinum (Pt), and/or combinations thereof. The catalyst may be a supported catalyst or an unsupported catalyst. According to some aspects, a combination of two or more metals may be used, for example, an iron, nickel, and cobalt mixture. In one example, the mixture may comprise a 50:50 mixture (by weight) of nickel and cobalt. The catalyst may comprise a pure metal, a metal oxide, a metal carbide, a nitrate salt of a metal, other compounds containing one or more of the metals described herein, and/or a combination thereof.

As used herein, the term “catalyst precursor” refers to a component that can be converted into an active catalyst. Examples of catalyst precursors include, but are not limited to, transition metal salts, such as a nitrate, acetate, citrate, chloride, fluoride, bromide, iodide, and/or hydrates thereof, and combinations thereof. For example, the catalyst precursor may be a metallocene, a metal acetylacetonate, a metal phthalocyanine, a metal porphyrin, a metal salt, a metalorganic compound, a metal sulfate, a metal hydroxide, a metal carbonate, or a combination thereof. For example, the catalyst precursor may be a ferrocene, nickelocene, cobaltocene, molybdenocene, ruthenocene, iron acetylacetonate, nickel acetylacetonate, cobalt acetylacetonate, molybdenum acetylacetonate, ruthenium acetylacetonate, iron phthalocyanine, nickel phthalocyanine, cobalt phthalocyanine, iron porphyrin, nickel porphyrin, cobalt porphyrin, an iron salt, a nickel salt, cobalt salt, molybdenum salt, ruthenium salt, or a combination thereof. The catalyst precursor may comprise a soluble salt such as Fe(NO₃)₃, Ni(NO₃)₂ or Co(NO₃)₂ dissolved in a liquid such as water. The catalyst precursor may achieve an intermediate catalyst state in the catalyst particle growth zone of the reactor, and subsequently become converted to an active catalyst upon exposure to the nanostructure growth conditions in the nanostructure growth zone of the reactor. For example, the catalyst precursor may be a transition metal salt that is converted into a transition metal oxide in the catalyst particle growth zone, then converted into active catalytic nanoparticles in the nanostructure growth zone.

It should be understood that while FIG. 1A shows a carbon source chamber 13 containing both a carbon source and a catalyst and/or catalyst precursor, the carbon source chamber 13 in fluid communication with the reactor 11 via the first inlet 12, the carbon source and the catalyst and/or catalyst precursor may be provided in separate chambers optionally in fluid communication with the reactor 11 via separate inlets.

The carbon source and catalyst and/or catalyst precursor may be provided to the reactor via a carrier gas, such as an inert carrier gas. For example, FIG. 1A shows the carbon source and catalyst and/or catalyst precursor provided to the reactor 11 via a helium (He) gas. Examples of inert gases useful according to the present disclosure include, but are not limited to, gases comprising helium (He), radon (Rd), neon (Ne), argon (Ar), xenon (Xe), nitrogen (N), and combinations thereof.

As shown in FIG. 1A, the reactor 11 may be provided with a second inlet 14. The second inlet 14 may be in fluid communication with, for example, a hydrogen gas source, which may be provided to provide a higher growth yield and/or to control SWNT vs. MWNT production. Hydrogen gas may additionally or alternatively be provided via a third inlet 15 that is in fluid communication with a carbon source chamber passage 16, the carbon source chamber passage 16 configured to provide fluid communication between the carbon source chamber 13 and the first inlet 12. In reactor 11, floating carbon nanotubes 17 can be grown, as shown in FIG. 1A. As used herein, the term “floating” refers to a state of being suspended, for example, suspended in a gas or liquid. As shown in FIG. 1A, the floating carbon nanotubes 17 may be suspended in the inert gas as described herein. The temperature of the reactor 11 may be maintained and/or varied using one or more heat sources 18 a and 18 b. In an illustrative example, heat sources 18 a and 18 b may individually or together comprise a furnace or a lamp. The one or more heat sources 18 a and 18 b may be proximal to reactor 11 and may maintain the temperature of reactor 11 at a temperature suitable for reducing the catalyst precursor into active catalyst and/or for the synthesis and/or formation of carbon nanotubes. According to some aspects, the one or more heat sources 18 a and 18 b may maintain the temperature of reactor 11 at a temperature of between about 300 and 1800° C., optionally between about 450 and 1600° C.

The method may comprise providing a structure including, but not limited to, a mat of the carbon nanotubes, alternatively referred to herein as a “web.” As used herein, the term “mat” or “web” refers to a tangled or bundled mass, such as a tangled, non-densified mass formed downstream of the nanotube growth zone by the floating carbon nanotubes. The mat of carbon nanotubes may be provided, for example, in and/or on the reactor and/or by continuously pulling the floating carbon nanotubes from the reactor. For example, FIG. 1A shows an example of floating carbon nanotubes 17 prepared in a nanotube growth zone of reactor 11. A mat of carbon nanotubes 110 may then form in reactor 11 downstream of the nanotube growth zone. The mat of carbon nanotubes 110 may deposit on the inner walls of reactor 11 and/or along the edges of outlet 19 of reactor 11. The mat of carbon nanotubes 110 may be pulled from reactor 11 through outlet 19 via a high flow rate of the carrier gas and/or hydrogen gas, as described herein. FIG. 2 shows an SEM image of a pure carbon nanotube mat, for example, a mat of carbon nanotubes 110 as shown in FIG. 1A. FIG. 3 shows a photograph of a pure carbon nanotube mat, for example, a mat of carbon nanotubes 110 as shown in FIG. 1A.

The method may comprise depositing a secondary material on at least a portion of the carbon nanotubes to provide a carbon nanotube composite yarn. According to some aspects, the method may comprise depositing a secondary material on at least a portion of the mat of carbon nanotubes to provide a carbon nanotube composite mat followed by a densification step wherein the carbon nanotube composite mat is densified to provide a carbon nanotube composite yarn. The method can comprise a simultaneous deposition and densification step, wherein the secondary material is deposited on at least a portion of the mat of carbon nanotubes while the mat of carbon nanotubes is simultaneously densified to provide a carbon nanotube composite yarn. According to some aspects, the deposition and/or densification steps may be continuous steps performed in parallel with continuously pulling the mat of carbon nanotubes from the reactor, as described herein.

As used herein, the term “secondary material” refers to a material comprising at least one material that is different from the carbon nanotube mat. Examples of materials useful as secondary materials according to the present disclosure include, but are not limited to, electrode active material(s), metals, metal oxides, lithium metal oxides, lithium iron phosphate, ceramics, carbon-based materials, and combinations thereof. Examples of carbon-based materials include, but are not limited to, graphite particles, graphite and graphene flakes, hard carbon, and combinations thereof.

In an illustrative example, the carbon-based material is an electrode active material for use in an electrode of a battery. Electrode active materials can be metal oxides. Examples of metal oxides include, but are not limited to, any metal oxide that may be used as an electrode active material in an electrode. In an illustrative example, the metal oxide is a material for use in the cathode of a battery. Non-limiting examples of metal oxides include those that comprise Ni, Mn, Co, Al, Mg, Ti, or any mixtures thereof. The metal oxide may be lithiated. In an illustrative example, the metal oxide is lithium nickel manganese cobalt oxide (LiNiMnCoO₂), Li(Ni,Mn,Co)O₂, Li—Ni—Mn—Co—O, or (LiNi_(x)Mn_(y)Co_(z)O₂, x+y+z=1). The metal oxide can be represented by Li-Me-O. Metals in lithium metal oxides according to the present disclosure may include, but are not limited to, one or more alkali metals, alkaline earth metals, transition metals, aluminum, or post-transition metals, and hydrates thereof. According to some aspects, the electrode active material is selected from graphite, hard carbon, metal oxides, lithium metal oxides, and lithium iron phosphate. According to some aspects, the electrode active material for the anode may be a carbon-based material as described herein, including but not limited to graphite particles, graphite flakes, graphene flakes, hard carbon, and combinations thereof. The electrode active material may be any solid, metal oxide powder that is capable of being aerosolized. The metal oxide powders can have a particle size defined within a range between about 1 nanometer and about 100 microns. In a non-limiting example, the metal oxide particles have an average particle size of about 1 nanometer to about 10 nanometers.

According to some aspects, carbon nanotube yarn-based composite, flexible self-standing electrodes for anode and cathode are formed by incorporation of graphite flakes or Li-Me-O particles, correspondingly in CNT yarn. The tread like electrodes can optionally be twisted together and electrolyte can be added following by covering with polymer-based insulator material. A copper (or other metal) layer can be deposited on the surface of thread like battery with a desired thickness. The surface layer of the resulting cable or MCW serves as a typical conductor for AC current (e.g., for electrical vehicle motor) while the “core” of the cable can provide the energy as a battery (FIG. 6B). The thickness of deposited Cu layer can be varied depending on frequency of exploited AC current. The terms cable and MCW are utilized interchangeable herein to refer to various embodiments of multifunctional conductive wire. The term cable does not limit the MCW disclosed herein to one insulator layer or one outer conductive metal layer because the MCW disclosed herein can have, in various embodiments, more than one insulator layer and more than on conductive metal or current carrier layer.

“Alkali metals” are metals in Group I of the periodic table of the elements, such as lithium, sodium, potassium, rubidium, cesium, or francium.

“Alkaline earth metals” are metals in Group II of the periodic table of the elements, such as beryllium, magnesium, calcium, strontium, barium, or radium.

“Transition metals” are metals in the d-block of the periodic table of the elements, including the lanthanide and actinide series. Transition metals include, but are not limited to, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, actinium, thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and lawrencium.

“Post-transition metals” include, but are not limited to, gallium, indium, tin, thallium, lead, bismuth, or polonium.

The term “electrode” refers to an electrical conductor where ions and electrons are exchanged with an electrolyte and an outer circuit. “Positive electrode” and “cathode” are used synonymously in the present description and refer to the electrode having the higher electrode potential in an electrochemical cell (i.e. higher than the negative electrode). “Negative electrode” and “anode” are used synonymously in the present description and refer to the electrode having the lower electrode potential in an electrochemical cell (i.e. lower than the positive electrode). Cathodic reduction refers to a gain of electron(s) of a chemical species, and anodic oxidation refers to the loss of electron(s) of a chemical species.

According to some aspects, the secondary material may be provided as secondary particles that are deposited on at least a portion of the mat of carbon nanotubes. According to some aspects, the particles may have a particle size from about 1 nanometer to about 100 microns, optionally from about 1 nanometer to about 10 nanometers. FIG. 1A shows a secondary particle chamber 111 containing secondary particles 112 as described herein. The secondary particle chamber 111 may comprise at least one outlet 113 proximal to outlet 19 of reactor 11. In this way, the mat of carbon nanotubes 110 leaving reactor 11 via outlet 19 may be subjected to secondary particles 112. While FIG. 1A shows only one secondary particle chamber 111, two, three, or more secondary particle chambers may be provided, wherein each of the plurality of secondary particle chambers comprises the same type or a different type of secondary particles from at least one other of the plurality of secondary particle chambers.

The secondary particle chamber 111 and delivery mechanism is not limited. In a non-limiting example, the secondary particle chamber 111 may include one or more of belt feeders, gravimetric feeders, pneumatic feeders, vacuum feeders, screw feeders, vibratory feeders, volumetric feeders, and valves.

According to some aspects, the secondary particles may be provided via one or more carriers. Examples of carriers include any substance known in the art configured to supply secondary particles to a substrate (for example, a mat of carbon nanotubes) as described herein without damaging the carbon nanotubes and/or the secondary particles. Examples of suitable carriers include gas carriers, liquid carriers, and combinations thereof. Example gas carriers include, but are not limited to, Ar, He, N₂, dry air, and combinations thereof. Example liquid carriers include, but are not limited to, water, acetone, ethanol, and combinations thereof. According to some aspects, the one or more carriers may be provided with the secondary particles 112 in the secondary particle chamber 111, as shown in FIG. 1A. Alternatively or additionally, one or more additional carrier chambers (not shown) may be provided such that the carrier and secondary particles are in communication prior to being deposited on the mat of carbon nanotubes. It should also be understood that a carrier may be excluded from the process as described herein such that the secondary particles are deposited on at least a portion of the mat of carbon nanotubes, for example, as a powder.

FIG. 1A shows a carbon nanotube composite mat 114 comprising at least a portion of secondary particles 112. FIG. 4 shows an SEM image of a carbon nanotube composite mat, for example, a carbon nanotube composite mat 114 as shown in FIG. 1A, comprising carbon nanotubes and a metal oxide powder. According to some aspects, the carbon nanotube composite mat may comprise 90% (w/w) or less carbon nanotube, optionally 80% (w/w) w/w or less, optionally 70% (w/w) w/w or less, optionally 60% (w/w) w/w or less, optionally 50% (w/w) w/w or less, optionally 40% (w/w) w/w or less, optionally 30% (w/w) w/w or less, optionally 20% (w/w) w/w or less, optionally 10% (w/w) w/w or less, optionally 9% (w/w) w/w or less, optionally 8% (w/w) w/w or less, optionally 7% (w/w) w/w or less, optionally 6% (w/w) w/w or less, optionally 5% (w/w) w/w or less, optionally 4% (w/w) w/w or less, optionally 3% (w/w) w/w or less, optionally 2% (w/w) w/w or less, and optionally 1% (w/w) w/w or less. According to some aspects, the carbon nanotube composite mat may comprise 10% (w/w) or more secondary particles, optionally 20% (w/w) or more secondary particles, optionally 30% (w/w) or more secondary particles, optionally 40% (w/w) or more secondary particles, optionally 50% (w/w) or more secondary particles, optionally 60% (w/w) or more secondary particles, optionally 70% (w/w) or more secondary particles, optionally 80% (w/w) or more secondary particles, optionally 90% (w/w) or more secondary particles, optionally 91% (w/w) or more, optionally 92% (w/w) or more, optionally 93% (w/w) or more, optionally 94% (w/w) or more, optionally 95% (w/w) or more, optionally 96% (w/w) or more, optionally 97% (w/w) or more, optionally 98% (w/w) or more, and optionally 99% (w/w) or more. According to some aspects, the carbon nanotube composite mat may comprise from 0.1% to 4% (w/w) carbon nanotubes, and the balance secondary particles and optionally one or more additives. Optionally, the carbon nanotube composite mat may comprise from 0.2% to 3% (w/w) carbon nanotubes, and the balance secondary particles and optionally one or more additives. Optionally the carbon nanotube composite mat may comprise from 0.75% to 2% (w/w) carbon nanotubes, and the balance secondary particles and optionally one or more additives. Additives and/or dopants may be present for each range in an amount of from 0 to 5% (w/w). In a non-limiting example, the carbon nanotube composite mat consists essentially of the carbon nanotubes and the secondary particles. In a non-limiting example, the carbon nanotube composite mat consists of the carbon nanotubes and the secondary particles.

The method may comprise densifying the carbon nanotube composite mat to provide a carbon nanotube composite yarn as described herein. For example, the carbon nanotube composite mat may be subjected to a liquid bath and/or a rolling press and/or a spindle and/or a cylindrical pipe and/or a tube, such as by spinning, pulling, and/or passing the carbon nanotube composite mat through or around the liquid bath and/or the rolling press and/or the spindle and/or the cylindrical pipe and/or the tube. In this way, the carbon nanotube composite mat 114 may be compacted to provide a carbon nanotube composite yarn 115, for example, as shown in FIG. 1A.

As shown in FIG. 1A, the carbon nanotube composite yarn 115 may be further processed, for example, by spinning the carbon nanotube composite yarn 115 around a spool 116. Alternatively, or additionally, the further processing step(s) may comprise removing excess secondary material from the carbon nanotube composite mat and/or the carbon nanotube composite yarn, for example, via shaking. One or more of the further processing step(s) may occur prior to and/or after the densification step(s) as described herein.

FIG. 1B shows two example densification steps as described herein. In particular, FIG. 1B shows floating carbon nanotubes 17 grown in a reactor 11 to provide a mat of carbon nanotubes 110, for example, as described in relation to FIG. 1A. FIG. 1B further shows a secondary particle chamber 111 containing secondary particles 112 as described in relation to FIG. 1A. FIG. 1B further shows two example densification steps, including a spinning densification step 117 and a liquid bath densification step 118. In particular, a spinning densification step 117 may comprise spinning a carbon nanotube composite mat 114 (carbon nanotube composite mat 114 comprising at least a portion of secondary particles 112 as described herein) through or around a rolling press and/or a spindle in order to form a carbon nanotube composite yarn 115 as described herein, similar to the example shown in FIG. 1A.

FIG. 1B also shows a liquid bath densification step 118, which may be performed instead of or in addition to spinning densification step 117. As shown in FIG. 1B, liquid bath densification step 118 may comprise subjecting a carbon nanotube composite mat 114 as described herein to a liquid bath 119 comprising a solvent. According to some aspects, the solvent may be any solvent known in the art configured to densify a mat of carbon nanotubes as described herein. Example solvents include, but are not limited to, water, acetone, ethanol, and combinations thereof. It should be understood that subjecting the carbon nanotube composite mat 114 to the liquid bath 119 comprising the solvent may provide a carbon nanotube composite yarn 115, as shown in FIG. 1B, which may be further processed as described herein, for example, by spinning the carbon nanotube composite yarn 115 around a spool 116. The further processing step(s) may be selected such that at least a portion of the solvent adhered to the carbon nanotube composite yarn 115 after it has been subjected to liquid bath 119 evaporates from the carbon nanotube composite yarn 115.

The method may comprise a simultaneous deposition and densification step as described herein, wherein the secondary material is deposited on at least a portion of the mat of carbon nanotubes while the mat of carbon nanotubes is simultaneously or about simultaneously densified to provide a carbon nanotube composite yarn. For example, the carrier as described herein may be configured to simultaneously deposit the secondary particles on the mat of carbon nanotubes and densify the mat of carbon nanotubes. One non-limiting example of such a step comprises the use of a solvent as described herein, wherein the solvent is used as a carrier to deposit the secondary particles on the mat of carbon nanotubes, as described herein. The solvent may simultaneously densify the mat of carbon nanotubes as described herein (e.g., as described in relation to liquid bath densification step 118 shown in FIG. 1B) to provide a carbon nanotube composite yarn. It should be understood that the simultaneous deposition and densification step may be performed instead of or in addition to one or more other steps as described herein, including one or more additional deposition steps, one or more additional densification steps, one or more additional simultaneous deposition and densification steps, one or more additional processing steps, and combinations thereof, wherein each additional step is individually performed before or after the simultaneous deposition and densification step.

The entire process for making the carbon nanotube composite yarn may be a continuous process. For example, the carbon source may be fed continuously to the reactor 11 so that the carbon nanotube mat may be continuously fed to the secondary particle chamber 111 for continuous deposition of the secondary particles, and the resulting composite structure may be continuously processed to form the carbon nanotube composite yarn. It is to be understood, however, that one or more stages may be performed separately in a continuous, batch, or semi-batch operation. For example, individual segments of carbon nanotube mats may be fed to the secondary particle chamber 111 for deposition of the particles thereon. The resulting composite structure may go through additional processing to evenly distribute the particles throughout the carbon nanotube mat.

After varying degrees of densification, the carbon nanotube composite yarn is a self-standing flexible electrode, and the carbon nanotube composite yarn can optionally be covered externally with a separator membrane. As a self-standing flexible electrode, the carbon nanotube composite yarn can comprise carbon nanotubes as described herein having secondary particles as described herein deposited thereon. The carbon nanotube yarn can be an electrode (such as an electrode for a battery), an electrode for a multifunctional conductive wire, a supercapacitor, a solar cell, a thermoelectric material, a sensor, an actuator, an element of an electronic device, an interconnect, or an E-textile, depending on the densification, dopants, secondary particles, and various conditions used during or after production of the carbon nanotube composite yarn.

The self-standing flexible electrodes can be internal to a cable having at least two electrodes, and optionally one or more separator membranes between the at least two electrodes in some cases (e.g., in the use of liquid electrolyte), wherein at least one of the electrodes comprises a carbon nanotube composite yarn as disclosed herein. According to some aspects, at least two of the electrodes each comprises a carbon nanotube composite yarn as disclosed herein. The cable may further comprise an electrolyte, an insulator layer, and a conducting layer.

FIG. 5A shows an example cable or MCW according to aspects of the present disclosure. In particular, FIG. 5A shows a cable having a first electrode 51 (e.g., an anode) and a second electrode 52 (e.g., a cathode), wherein each of the first and second electrodes individually comprises a carbon nanotube composite yarn as disclosed herein. For example, the first electrode 51 may comprise a carbon nanotube composite yarn wherein the secondary material comprises graphite flakes, and the second electrode 52 may comprise a carbon nanotube composite yarn wherein the secondary material comprises Li-Me-O particles.

According to some aspects, the cable or MCW may comprise the first electrode 51 and the second electrode 52 in a coaxial configuration, that is, wherein an axis of the first electrode 51 and an axis of the second electrode 52 are parallel or quasi-parallel, as shown in FIG. 5A. It should be understood that in this example, “quasi-parallel” refers to a relationship between the axes such that the axes extend in the same direction and do not overlap one another. According to some aspects, the cable or MCW may comprise the first electrode 51 and the second electrode 52 in a twisted configuration. It should be understood that a “twisted configuration” may refer to a configuration wherein the first electrode 51 and the second electrode 52 are wrapped around one another.

According to some aspects, the first electrode 51 and the second electrode 52 may be separated from each other by a separator membrane (e.g., a nafion membrane). For example, FIG. 5A shows an expanded view 56 of the first electrode 51, which includes a carbon nanotube composite yarn as described herein. The first electrode 51 may be surrounded by a separator membrane 57 as described herein. The second electrode 52 may have a similar configuration. It should be understood that in some cases, neither the first nor second electrode may be surrounded by a separator membrane, one of the first and second electrode may be surrounded by a separator membrane, or both the first and second electrode may be surrounded by a separator membrane. According to some aspects, the first electrode 51 and the second electrode 52 are not in direct contact with each other.

The MCW or cable may further comprise an electrolyte (e.g., a liquid, gel, solid, or combination thereof) 53 substantially surrounding the first electrode 51 and the second electrode 51, an insulator layer 54 substantially surrounding the electrolyte 53, and a conducting layer 55 substantially surrounding the insulator layer 54.

FIG. 5B shows an example cross-sectional schematic of an MCW according to aspects of the present disclosure, including a first electrode 51, a second electrode 52, and an insulator layer 54 substantially surrounding an electrolyte 53 (in this example, a liquid electrolyte), as described herein. In this example, first electrode 51 and second electrode 52 are surrounded by separator membranes 57 a and 57 b, respectively, as described herein.

FIG. 5C shows another example cross-sectional schematic of an MCW according to aspects of the present disclosure. Similar to FIG. 5B, FIG. 5C shows a first electrode 51, a second electrode 52, and an insulator layer 54 substantially surrounding an electrolyte 53 (in this example, a liquid electrolyte), as described herein. In this example, only the second electrode 52 is surrounded by a separator membrane 57 b as described herein. It should be understood that in some examples, only the first electrode 51 may be surrounded by a separator membrane (not shown in FIG. 5C).

FIG. 5D shows another example cross-sectional schematic of an MCW according to aspects of the present disclosure. Similar to FIGS. 5B and 5C, FIG. 5D shows a first electrode 51, a second electrode 52, and an insulator layer 54 substantially surrounding an electrolyte 53 (in this example, a liquid electrolyte), as described herein. In this example, neither the first electrode 51 nor the second electrode 52 may be surrounded by a separator membrane 57. In this example, a distinct separator membrane 501 may be provided between the first electrode 51 and the second electrode 52.

FIG. 5E shows another example cross-sectional schematic of an MCW according to aspects of the present disclosure. Similar to FIGS. 5B-5D, FIG. 5E shows a first electrode 51, a second electrode 52, and an insulator layer 54 substantially surrounding an electrolyte 53, as described herein. In this example, the electrolyte 53 may be a solid and/or a gel electrolyte, and as such, no separator membranes may be required.

Materials useful for the electrolyte include, but are not limited to, mixtures of alkyl carbonates (e.g., ethylene carbonate (EC), dimethyl (DMC), diethyl (DEC), and ethyl-methyl carbonates (EMC)) and LiPF₆ as the electrolyte solution as well as gel and solid electrolytes.

Materials useful for the insulator layer include, but are not limited to, non-conductive materials such as polymer-based materials. Example non-conductive polymer-based materials include plastics such as polyethylene.

Materials useful for the conducting layer include, but are not limited to, materials capable of conducting AC current such as copper, nickel, aluminum, and alloys thereof. In one example, the conducting layer 55 comprises copper. According to some aspects, the thickness of the conducting layer 55 may be selected based on the frequency of exploited AC current. For example, at 60 Hz in copper, AC has a skin depth of about 7 to 8.5 mm. For higher frequency AC, the thickness of the conducting layer can be thinner without adding resistance. According to some aspects, an intended current (amperage) can also determine a thickness of the conducting layer. According to some aspects, the thickness of the conducting layer may be between about 1 μm to about 10 mm. However, the thickness of the conducting layer is not limited. An insulator layer can be applied over the conducting layer, and further conducting layers can be applied over this insulator layer. For example, an electromagnetic shielding (or RF shielding) layer can be applied over the entire MCW, and this shielding layer can be covered with insulator.

The depth to which AC current penetrates in a conductor can be defined by a skin depth, which can be described as the depth at which the current is reduced to 37% of its surface value. The skin depth decreases with frequency. At low frequencies at which the skin depth is larger than the diameter of the wire, the skin effect is negligible, and the current distribution and resistance are virtually the same as at DC. As the frequency rises and the skin depth gets smaller than the wire diameter, skin effect becomes significant, the current is increasingly concentrated near the surface, and the resistance per unit length of wire increases above its DC value. Non-limiting examples of skin depth in copper wire at different frequencies are at 60 Hz, the skin depth of a copper wire is about 0.3 inches (7.6 mm); at 60 kHz, the skin depth of copper wire is about 0.01 inches (0.25 mm); at 6 MHz, the skin depth of copper wire is about 0.001 inches (25 μm). Round conductors such as wire or cables larger than a few skin depths do not conduct much current near their axis, so the metal located at the central part of the wire is not used effectively.

It should be understood that the cable or MCW according to the present disclosure, for example, as shown in FIGS. 5A-5D, may function as both a conductor for AC (e.g., for use in an electrical vehicle motor) and a battery. In particular, at least the first electrode, the second electrode, and the electrolyte may together provide energy while the conducting layer may transmit electrical current. The MCW disclosed herein can be utilized for DC and, optionally, can switch from AC to DC, DC to AC, and can be utilized for any range of AC frequencies. According to some aspects, the one or more conductive layers can comprise insulated conductors, such that a conductive layer has multiple conductors therein. The MCW can have additional MCW in any layer surrounding the MCW.

As shown in FIG. 5A, the self-standing flexible electrodes can have one or more conductive battery tabs 58 which can provide an area for electrically connecting or for attaching the electrode to an external component or device. The conductive battery tabs can be utilized to connect an electrode to the conductive metal layer or current carrier layer of MCW. The conductive battery tabs can be attached to or embedded in the flexible self-standing electrodes by any means. The conductive battery tabs are not current collectors, for example, a metal substrate for the electrode, prone to peeling and breaking. The self-standing flexible electrodes disclosed herein can be free of current collector and free of binder. According to some aspects, the battery tab can comprise a different material at or near the area of attachment to the flexible self-standing electrode and a different material external to the MCW or extending from the MCW. Battery tabs can be attached to the electrodes, in accordance with aspects of the present disclosure, either to protrusions extending from the main body of the respective electrode and not overlapping with the other electrode; or to the main body of the respective electrode at cutouts of a separator membrane and the opposing electrode. According to some aspects, battery tabs are embedded into the electrodes. Suitable battery tab materials and methods of attachment include those known to persons of ordinary skill in the art. According to some aspects, the conductive battery tabs can comprise copper or lead for the anode. According to some aspects, the conductive battery tabs can comprise aluminum or lead for the cathode. According to some aspects, the battery tabs can comprise one metal at or near attachment to the electrode and a different metal extending away from the electrode, for example, a stretchable and flexible spring metal as a stretchable and flexible battery tab attachment. According to some aspects, flexible or inflexible battery tab attachments 59 are attached to the conductive battery tabs. The battery tab attachments 59 can be attached to the battery tabs 58 by any means known in the art, for example, soldering, welding, pressing, or interlocking components. The battery tab attachments 59 can be used to connect the electrodes to any external component, article, or device. The battery tabs 58 or battery tab attachments 59 can be used to connect the electrodes to one or more conductive layers or current carriers in the MCW. For example, the battery tabs or battery tab attachments can be connected to a component utilized to convert DC to AC and further connected to a conductive layer. The battery tabs 58 or battery tab attachments 59 can be located at one or more exposed ends of MCW or can be located along any position along the MCW. According to some aspects, a length of MCW can comprise multiple battery tabs 58 or battery tab attachments 59.

Any electrical device or article can incorporate the MCW as described herein, including, for example, an electrical vehicle motor. Conventional electrical vehicle motors, such as the electrical motor 61 shown in FIG. 6A, generally require external batteries 62A and 62B to create torque via induced electromagnetic fields. As shown in FIG. 6A, such electrical motors can generally comprise copper coils 63, which transmit electrical current that generates a magnetic field and/or which accumulate electrical current induced by an external magnetic field. According to some aspects, MCW can be utilized in place of solid copper wires in the copper coils 63; the MCW can have an outer square or rectangular shape to improve nesting in a winding of a coil in an electrical device.

FIG. 6B shows one illustrative aspect of the present disclosure, specifically an electrical vehicle motor 601. As shown in FIG. 6B, an electrical vehicle motor 601 may include one or more MCW coils 602 in place of one or more of the copper coils 63 generally provided in conventional electrical vehicle motors (as shown, for example, in FIG. 6A). The one or more MCW coils 602 may comprise a MCW coil having a configuration as described, for example, in relation to FIG. 5A. The MCW coil may comprise two electrodes 603 in a twisted configuration, an electrolyte 604, an insulator layer 605, a conducting layer 606, and a battery tab attachment 59 as described in relation to FIG. 5A. According to some aspects, the MCW coils 602 may be configured to both transmit electrical current and partially or completely power the electrical vehicle motor 601, thereby reducing or eliminating the need for an external battery (for example, external batteries 62A and 62B shown in FIG. 6A). The electrical motor 61 shown in FIG. 6B is a non-limiting example and can represent a solenoid, a generator, an alternator, and a transformer, any of which comprise MCW according to various aspects of the present disclosure.

In one example, the electrical vehicle motor according to the present disclosure may include a stator having one or more stator coils and a rotor. According to some aspects, at least a portion of the one or more stator coils may comprise an MCW coil as described herein. Additionally or alternatively, the rotor may comprise one or more rotor coils, wherein at least a portion of the one or more rotor coils comprises an MCW coil as described herein. The electrical vehicle motor may further comprise, for example, a commutator provided in electrical communication with the one or more rotor coils and a brush contacting the commutator.

One non-limiting example of an electrical vehicle motor useful according to the present disclosure is described in U.S. Patent Publication No. 2019/068033 A1, the disclosure of which is incorporated herein in its entirety. It should be understood that that the motor described in U.S. Patent Publication No. 2019/068033 A1 may comprise one or more MCW coils of the present disclosure in addition to the coils as described therein. For example, a permanent magnet of the stator may be formed by or replaced with a stator coil comprising an MCW coil, which serves as a permanent magnet. Additionally or alternatively, one or more of the coils described in U.S. Patent Publication No. 2019/068033 A1 may be replaced with one or more MCW coils according to the present disclosure.

The present disclosure is also directed to methods of using the carbon nanotube composite yarns prepared according to the methods described herein. For example, a method may comprise preparing an article or device as described herein comprising the carbon nanotube composite yarns. For example, the method may comprise weaving the carbon nanotube composite yarns to provide an E-textile. The method may comprise preparing a MCW or cable as described herein. For example, the method may comprise providing a first electrode (e.g., an anode) and a second electrode (e.g., a cathode) in an optional twisted configuration and separated by one or more separator membranes and/or an electrolyte, wherein each of the first and second electrodes individually comprises a carbon nanotube composite yarn as disclosed herein. The method may further comprise providing an electrolyte surrounding the first and second electrodes, providing an insulator layer surrounding the electrolyte, and providing a conducting layer surrounding the insulator layer.

According to some aspects, a method of making an MCW may comprise providing a first flexible electrode comprising a first carbon nanotube composite yarn containing carbon nanotubes and a first secondary material (e.g., first secondary particles); providing a second flexible electrode comprising a second carbon nanotube composite yarn containing carbon nanotubes and a second secondary material (e.g., second secondary particles); optionally surrounding the first flexible electrode with a first separator membrane; optionally surrounding the second flexible electrode with a second separator membrane; surrounding the first and second flexible electrodes with an electrolyte; surrounding the electrolyte with a flexible insulator layer; and at least partially surrounding the flexible insulator layer with a flexible conducting layer.

It should be understood that the steps as described herein are not limited to one order. For example, in the case of a liquid electrolyte, the method of making the MCW may comprise providing a first flexible electrode and a second flexible electrode in a configuration as described herein (e.g., in a parallel, quasi-parallel, or twisted configuration), wherein the first flexible electrode and the second flexible electrode are provided with a first separator membrane and a second separator membrane, respectively, and/or a distinct separator membrane is provided between the first flexible electrode and the second flexible electrode, as described herein. The method may further comprise providing the first and second flexible electrodes in an insulator layer as described herein and subsequently surrounding the first and second flexible electrodes with an electrolyte as described herein. In this example, a flexible conducting layer may be provided before, during, or after any step as described herein.

In another example, in the case of a solid or gel electrolyte, the method of making the MCW may comprise providing the electrolyte in communication with (e.g., on a surface of and/or immersed in) a first flexible electrode and a second flexible electrode, wherein the first flexible electrode and/or the second flexible electrode are independently provided with or without a first separator membrane and/or a second separator membrane, respectively. It should be understood that the first separator membrane and/or the second separator membrane may independently be provided before, during, and/or after the electrolyte is provided, or the first separator membrane and/or the second separator membrane may be excluded. The method may further comprise subsequently providing the first electrode and the second electrode in a configuration as described herein (e.g., in a parallel, quasi-parallel, or twisted configuration). In this example, the first and second electrodes may be provided in an insulator layer before, during, or after they are provided in their final configuration. Furthermore, in this example, a flexible conducting layer may be provided before, during, or after any step as described herein.

According to some aspects, providing a flexible conducting layer as described herein may be performed via any technique useful according to the present disclosure. For example, the flexible conducting layer may be provided using an electrodeposition technique, an electroplating technique, or a combination thereof. In one non-limiting example, the flexible conducting layer may be provided via an electroplating technique that comprises providing an electric current which causes dissolved metal ions to adhere to a surface, for example, the surface of an insulator layer as described herein. In another non-limiting example, the flexible conducting layer may be provided as a pre-formed structure (e.g., a pre-formed elongated hollow body, such as a tube) in which a first flexible electrode, a second flexible electrode, a first separator membrane, a second separator membrane, an electrolyte, and/or a flexible insulator layer may be provided as described herein.

Methods to assemble an article or device comprising multifunctional conductive wire (MCW) are disclosed herein. For example, attaching MCW to one or more electrical components of a device, can assemble a device comprising MCW, wherein the MCW can provide current carrying capacity simultaneously with providing or storing power for a device. Winding MCW into a coil, optionally a metal core coil, and attaching the coil to a component can assemble a device or article comprising MCW. According to some aspects, a device or an article having MCW can be assembled by attaching MCW, as a current carrier and a source of power and/or power storage for a component of a device or an article.

A device or article comprising MCW can utilize MCW with a specific thickness of a conducting layer. According to some aspects, the thickness of a conducting layer can be determined according to the frequency of AC in a device. For DC, the resistance of a solid-metal conductor depends on its cross-sectional area; a conductor with a larger area has a lower resistance for a given length. At high frequencies, AC does not penetrate deeply into conductors due to eddy currents induced in the material; it tends to flow near the surface, known as skin effect. Since less of the cross-sectional area of the wire is being used, the resistance of the wire is greater than it is for DC. The higher the frequency of the current, the smaller the depth to which the current penetrates, and the current is carried into an increasingly smaller cross-sectional area along the surface, so the AC resistance of wire increases with frequency.

This detailed description uses examples to present the disclosure, including the preferred aspects and variations, and to enable any person skilled in the art to practice the disclosed aspects, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspect, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application.

According to some aspects, various electrical devices can incorporate MCW to make an electrical device more efficient, for example, having a greater power to weight ratio, having power storage capability without an external battery, or having power provided by the MCW. While the aspects described herein have been described in conjunction with the example aspects outlined above, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or that are or may be presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the example aspects, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure. Therefore, the disclosure is intended to embrace all known or later-developed alternatives, modifications, variations, improvements, and/or substantial equivalents.

Reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference. Moreover, nothing disclosed herein is intended to be dedicated to the public.

Further, the word “example” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as an “example” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C.

As used herein, the term “about” and “approximately” are defined to being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the term “about” and “approximately” are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%. 

What is claimed is:
 1. An electrical device comprising: a multifunctional conductive wire, said multifunctional conductive wire comprising: an elongated hollow body comprising a conductive material; a first electrode comprising a first carbon nanotube composite yarn comprising carbon nanotubes and a first secondary material; a second electrode comprising a second carbon nanotube composite yarn comprising carbon nanotubes and a second secondary material, wherein the multifunctional conductive wire is operative to carry current and to provide power and/or store power for the electrical device.
 2. The electrical device of claim 1, wherein the multifunctional conductive wire further comprises an electrolyte surrounding the first and second electrodes.
 3. The electrical device of claim 2, wherein the multifunctional conductive wire further comprises a flexible insulator layer surrounding the electrolyte, and wherein the conductive material comprises a flexible conducting layer at least partially surrounding the flexible insulator layer.
 4. The electrical device of claim 3, wherein the multifunctional conductive wire further comprises an outer flexible insulator layer surrounding the flexible conducting layer.
 5. The electrical device of claim 1, wherein the multifunctional conductive wire further comprises: one or more conductive battery tabs attached to the first electrode and/or the second electrode, and one or more respective battery tab attachments attached to the one or more conductive battery tabs.
 6. The electrical device of claim 1, wherein at least one of the first electrode and the second electrode is surrounded by a separator membrane, and wherein the first electrode and the second electrode are wrapped around each other in a twisted configuration.
 7. The electrical device of claim 1, wherein at least a portion of the multifunctional conductive wire is in a winding of one or more coils, each coil comprising a portion of the multifunctional conductive wire turned in the shape of a spiral or a helix.
 8. The electrical device of claim 7, wherein the portion of the multifunctional conductive wire in the winding of one or more coils has an outer square or rectangular shape, the outer square or rectangular shape operative to nest the multifunctional conductive wire in the winding of one or more coils.
 9. The electrical device of claim 7, wherein the winding of one or more coils surrounds a metal core.
 10. The electrical device of claim 3, wherein the flexible conducting layer has a thickness from about 1 micrometer to about 10 millimeters.
 11. The electrical device of claim 1, wherein the electrical device is selected from the group consisting of an electrical motor, a solenoid, a generator, an alternator, and a transformer.
 12. The electrical device of claim 1, wherein the conductive material comprises a flexible conducting layer comprising copper.
 13. The electrical device of claim 6, wherein the first separator membrane and the second separator membrane are not in contact with each other.
 14. A method of making an electrical device comprising a multifunctional conductive wire, the method comprising: providing a multifunctional conductive wire; connecting the multifunctional conductive wire to an electrical device such that the multifunctional conductive wire is operative to carry current and to provide power and/or store power for the electrical device.
 15. The method of claim 14, further comprising winding at least a portion of the multifunctional wire in a winding of one or more coils, each coil comprising a portion of the multifunctional conductive wire turned in the shape of a spiral or helix.
 16. The method of claim 14, wherein providing the multifunctional conductive wire comprises: providing a first electrode comprising a first carbon nanotube composite yarn comprising carbon nanotubes and a first secondary material; and providing a second electrode comprising a second carbon nanotube composite yarn comprising carbon nanotubes and a second secondary material.
 17. The method of claim 16, wherein providing the multifunctional conductive wire further comprises: surrounding the first and second electrodes with an electrolyte; surrounding the electrolyte with a flexible insulator layer; at least partially surrounding the flexible insulator layer with a flexible conducting layer; and surrounding the flexible conducting layer with an outer flexible insulator layer.
 18. The method of claim 17, wherein providing the multifunctional conductive wire further comprises: attaching one or more conductive battery tabs to the first electrode and/or the second electrode; and attaching one or more respective battery tab attachments to one or more of the conductive battery tabs.
 19. The method of claim 16, wherein providing the multifunctional conductive wire further comprises: surrounding at least one of the first electrode and the second electrode with a separator membrane; and wrapping the first electrode and the second electrode are around each other in a twisted configuration.
 20. The method of claim 16, wherein providing the first electrode comprises: growing floating carbon nanotubes in a reactor; removing the floating carbon nanotubes from the reactor to provide a mat of carbon nanotubes; depositing secondary particles comprising the first secondary material on at least a portion of the mat of carbon nanotubes to provide a carbon nanotube composite mat; and densifying the carbon nanotube composite mat to provide a carbon nanotube composite yarn.
 21. An electric motor comprising: a rotor comprising one or more rotor coils; and a stator comprising one or more stator coils, wherein at least a portion of the one or more stator coils comprises a conductive wire, and wherein the conductive wire comprises: an elongated hollow body; a first flexible electrode positioned in the hollow body and comprising a first composite yarn comprising carbon nanotubes and a first secondary material; a second flexible electrode positioned in the hollow body and comprising a second composite yarn comprising carbon nanotubes and a second secondary material.
 22. The electric motor of claim 21, wherein the conductive wire further comprises an electrolyte surrounding the first and second electrodes.
 23. The electric motor of claim 22, wherein the conductive wire further comprises a flexible insulator layer surrounding the electrolyte, and wherein the conductive material comprises a flexible conducting layer at least partially surrounding the flexible insulator layer.
 24. The electric motor of claim 23, wherein the conductive wire further comprises an outer flexible insulator layer surrounding the flexible conducting layer.
 25. The electric motor of claim 21 further comprising a commutator in electrical communication with the one or more rotor coils and a brush contacting the commutator. 